ME. LUBBOCK ON THE OVA AND PSEUDO YA OE INSECTS. 
367 
species from the type common in insects. A glance at the figures is sufficient to show 
this, so that it is unnecessary to enter into any detailed description. 
Each of the pseudova, even after it has attained its full length, is surrounded by a 
distinct layer of nucleated cells. The walls of the tube appear to be constituted by a 
dehcate, structureless membrane, so that I suppose it is the epithelial layer (consisting 
of nucleated cells) which has in some places detached itself from the outer membrane in 
order to form a close covering for the eggs. After the egg has arrived at maturity, this 
cellular layer gradually disappears. 
At the lower end, in Plate XVII. fig. 2, one of the eggs is elongating and pushing its 
narrow end up the tube. This process appears to be somewhat rapid, at least there is 
always at this stage a considerable difference between the form of the lowest egg and 
that of the one immediately preceding it. 
The egg gi-adually becomes longer and longer, the narrow end at the same time forcing 
itself up the tube ; and the other eggs successively undergo the same changes, until 
at length the ovarian tube offers the appearance represented in fig. 3, Plate XVII. The 
narrow ends now all lie at the upper end of the tube, and the swollen ends at the lower. 
The germinal vesicle is present, as usual in insects, but it remains visible longer than 
I have found to be the case in most other species, and indeed may be seen after the 
pseudovum has attained its mature form. 
The development of the pseudova of Solenobia lichenella appears also to offer no great 
peculiarities. Plate XVIII. fig. 17, copied from Leuckaet, represents one of the egg- 
tubes taken from a caterpillar of 8. lichenella, and it resembles, in all important parti- 
culars, a similar organ of any other Lepidopterous insect. The epithelial cells, the large 
vitelligenous cells with their nuclei, and the egg-cell itself, with its germinal vesicle, are 
all of the usual structure, and arranged in the ordinary manner. 
Many other Lepidoptera have presented us with individual instances of parthenoge- 
nesis, in which the eggs, though fertile without impregnation, were no doubt identical 
with the true ova, and would have been impregnated under ordinary circumstances *. 
In the Hive-bee, also, the ovarian development of the ova and pseudova must appa- 
rently be identical, since it would appear that in normal instances, it is not decided until 
after the ovarian product has entered the oviduct, whether it is to be an ovum or a 
pseudovum, in other words, whether it is to be impregnated or not. 
At the same time the sex of the future animal is determined, since, according to 
MM. Leuckaet and Siebold, eggs always in this species produce females, and pseudova 
give birth to males. 
We are then, I think, justified in asserting that in the present state of our knowledge 
no difference can be pointed out between the ovarian development of the pseudovum in 
insects and that of the true ovum. 
* M. Millieee has lately instituted a new genus, Agerona, which belongs to the same group of moths, 
and contains two new species, both of which multiply by parthenogenesis. Ann. de la Soc. Limi6enne de 
Lyon, 1857, vol. iv. p. 181. 
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